According to the recent trend of slimming and miniaturizing mobile communication terminals, vibration motors used in mobile communication terminals are required to have specifications including a 10.0 mm diameter and a 2.0 mm thickness.
FIG. 1 is a sectional view of a slim type vibration motor according to the related art, which will now be described.
As shown in FIG. 1, a conventional vibration motor 10 includes a yoke bracket 11 and a cover 13 that are coupled to form a predetermined space within, and a lower and upper portion of a shaft 15 are supported respectively by the yoke bracket 11 and the cover 13.
A stator base 17 is provided at the top surface of the yoke bracket 11, and a coil 19 is bonded to the top surface of the stator bracket 17. Also, a shaft receiving member 21 is provided around the shaft 15, and an eccentric rotor yoke 23 is fixed around the shaft receiving member 21. Magnets 25 and weights 27 are provided at the lower surface of the rotor yoke 23.
Thus, when a current is supplied to the coil 19, the coil 19 and magnet 25 interact so that the magnets 25, weights 27, and rotor yoke 23 rotate and generate vibrations.
Normal vibration motors have diameters of 10.0 mm and thicknesses of 2.6 mm, whereas slim type vibration motors have diameters of 10.0 mm and thicknesses of 2.0 mm. In order to form a slim type vibration motor, the thicknesses of the coil 19 and magnets 25 must be reduced.
However, in the slim type vibration motors according to the related art, when the coil 19 and magnets 25 are reduced in thickness, the ability to generate an adequate amount of torque is sacrificed. To increase the torque of a slim type vibration motor, the applied current can be increased; however, this consumes more power from the battery, reducing the time that the mobile communication terminal can be used on a single charge.